the nanoparticles found in ALH are simply to small. length: 380nm
wide range about 20nm.(Scientific american) ( 20-100 nanometres in diameter, wiki)
the diameter of a ribosome is about 20-25nm. in an E.Coli you can find about 20 000 ribosomes.
the smallest living beeing (Mycoplasma) has a diamter about 200nm. Staphylococcous aureus: 600nm....
the ALH84001 particles are to small to produce Proteins, no space for a metabolism etc.
The famous nanobacteria (for example Nanobacterium sanguineum)seems to be only anamorphic hydroxylapatite crystals (Ca2+ + PO42-) with proteins, lipids, DNA, RNA.. (sientific american)

In the article linked, below, we read that Dr. Wickramasinghe intended to fly to Sri Lanka to gather further information about the Polannaruwa meteorite, over the weekend of Jan. 19-20. He explains a bit about why he believes the object is a meteorite, albeit an unusual one, and where he believes it may have originated. Included in the article is an interesting quote from Sir Arthur C. Clarke. He seems to have seriously entertained the possibility that Hoyle and Wickramasinghe's panspermia hypothesis is correct. I recall another of Sir Arthur's famous quotes, to the effect that-- when an elderly scientists says something is impossible, he is usually wrong, and when he says some is or could be so, he is probably right. Ironically, this could now apply to Clarke himself, and to Wickramasinghe. http://www.lankaweb.com/news/items/2013/01/17/chandra-wickramasinghe-coming-to-sri-lankato-gather-further-information/

Some writers and publications have taken to charging, or repeating the charge that Dr. Wickramasinghe is a 'fringe scientist'. The context of these remarks make it clear that the intent is critical and dismissive. They are not describing or commending his work on the edge of what is known; seeking to expand scientific knowledge. I thought it would be interesting to look up the doctor's curriculum vitae, resume, honors, publications, and accomplishments. Below is a link to a summary of this impressive lifetime of scientific endeavor: http://www.buckingham.ac.uk/directory/professor-chandra-wickramasinghe/